PALEOHYDROGEOLOGICAL STUDIES OF THE ORIGIN AND DISSIPATION OF OIL AND GAS ACCUMULATIONS IN THE INSTANCE OF CIS-CAUCASIAN MESOZOIC DEPOSITS

The study of the hydrogeological evolution of a region or water-carrier complex may be of great importance in estimating the oil and gas prospects of either a region or the stratigraphic section. The cycle begins with transgression, sedimentation, and accumulation of sedimentation waters, and includes the stages of regression, denudation, and seepage, and culminates in a new transgression with cessation of seepage. Such cycles may be compound if a region, developed as a unit, is broken up into segments with different hydrogeological histories — some in the seepage stage while others are submerged and experiencing a new cycle.

Generalized paleohydrogeologic maps and cross-sections for the Mesozoic of the Cis-Caucasus, based on paleogeologic maps and other data by the I. M. Gubkin Joint Oil and Gas expedition of the Ministry of Economy and Mining Industry, are presented and represent either the seepage or infiltration stage. They show outcrops of water-carrier section, the lack of them, their occurrence beneath younger rocks and undersea. Four hydrogeologic stages, each consisting of two stages, are beginning with Middle Jurassic time Jurassic, Lower Cretaceous, Upper Cretaceous, and Cenozoic. --W. D. Lowry.